Method and apparatus for connecting flowlines to underwater wellheads

ABSTRACT

Apparatus and method for connecting flowlines to underwater wellheads by attaching a pulling head to the flowline and anchoring a pulling head fixture to the wellhead. A releasable pulling tool having a wireline in slidable engagement with the fixture on the wellhead is connected to the flowline pulling head and the head is pulled into engagement with the fixture. When in proper position, the pulling tool is released and fluid communication may then be provided between the wellhead and the pulling head and thus with the flowline.

United States Patent Petersen [54] METHOD AND APPARATUS FOR CONNECTING FLOWLINES TO UNDERWATER WELLHEADS [72] Inventor; William H. Petersen, Metairie, La.

[73] Assignee: Shell Oil Company, New York,

[22] Filed: July 29, 1970 [21] Appl. No.: 59,234

[52] US. Cl ..l66/.5, 61/723 [51] Int. Cl. ..E2lb 43/00 [58] Field of Search l 66/.5, .6; 61/723 [56] References Cited UNITED STATES PATENTS 3,585,805 6/1971 Vincent 166/.6 X 3,482,410 12/1969 Roesky et al. ..l66/.5 X

[ 51 Oct. 3, 1972 3,358,753 12/1967 Haeber ..l66/.6

Primary Examiner-Marvin A. Champion Assistant Examiner-Richard E. F avreau Attorney-Harold L. Denkler and Theodore E. Bieber ABSTRACT Apparatus and method for connecting flowlines to underwater wellheads by attaching a pulling head to the flowline and anchoring a pulling head fixture to the wellhead. A releasable pulling tool having a wireline in slidable engagement with the fixture on the wellhead is connected to the flowline pulling head and the head is pulled into engagement with the fixture. When in proper position, the pulling tool is released and fluid communication may then be provided between the wellhead and the pulling head and thus with the flowline.

8 Claims, 13 Drawing Figures PATENTEBMII Ill? 3,695,350

sum 2 or 6 INVENTOR.

WILLIAM H. PETERSEN FIG-4 f/wxw ATTORNEY PATENTEBnm 3 m2 SHEEI 4 [1F 6 A 144 pZM ATTORNEY PATENTED T 3 SHEET 5 BF 6 I N VENTOR.

Q @m/ wh/ mm Nb mm K on WILLIAM H. PETERSEN fi M/ 0 M EITORNEYS METHOD AND APPARATUS FOR CONNECTING FLOWLINES TO UNDERWATER WELLIIEADS BACKGROUND OF THE INVENTION I Field of the Invention The invention relates to underwater flowlines; and, more particularly, to a method and apparatus for connecting underwater flowlines to wellheads extending into the floor of a body of water.

2. Description of the Prior Art The development of offshore oil and gas wells involves the extension of wells into the ocean floor. It is often desirable to provide one or more flowlines from the wellhead of such wells to a remote point, as for example, to shore or another wellhead. The flowlines may serve many purposes, the most common being to carry off the output of oil or gas from the well. Since the flowline (also referred to as a pipeline) lays in a substantially horizontal position along the floor of the body of water, a problem arises in coupling such flowlines to the wellhead in a manner providing fluid communication therebetween.

Present flowline connecting equipment and methods have not proven satisfactory. There exists a need for flowline connecting equipment that can be used to readily and economically connect one or more flowlines to a wellhead on the ocean floor.

SUMMARY OF THE INVENTION It is an object of this invention to provide a method and apparatus for connecting one or more flowlines to a wellhead on the ocean floor.

It is a further object of this invention to provide a method and apparatus for pulling one or more flowlines into fluid communication with a wellhead on the ocean floor.

These and other objects are preferably accomplished by attaching a pulling head to the flowline and anchoring a pulling head fixture to the wellhead. A releasable pulling tool having a wireline in slidable engagement with the fixture on the wellhead is connected to the pipeline pulling head and the head is pulled into engagement with the fixture. When in proper position, the pulling tool is released and fluid communication may then be provided between the wellhead and the pulling head and thus the flowline.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a vertical sectional view of a wellhead guide structure for carrying out the techniques of my invention;

FIG. 2 is a top plan view of the guide structure of FIG. I;

F IG. 3 is a detailed view of one of the lower-half horn assemblies of the guide structure of FIGS. 1 and 2;

FIG. 4 is a vertical sectional view of the guide structure of FIG. I showing a Xmas-tree assembly in place on the structure;

FIG. 5 is a vertical sectional view of a surface work vessel and its relation to the wellhead equipment of FIG. 4 for carrying out the techniques of my invention;

FIG. 6 is a detailed view of a portion of the apparatus of FIG. 5;

FIG. 7 is a detailed view of a portion of the pull-in fixture of FIG. 6;

FIG. 8 is a vertical sectional view, similar to FIG. 4, showing the pull-in fixture of FIGS. 6 and 7 in place on the wellhead guide structure;

FIG. 9 is a vertical sectional view, similar to FIG. 5, showing a pipe laying vessel in conjunction with the work vessel for carrying out the techniques of my invention;

FIG. 10 is a vertical sectional view of a portion of the apparatus of FIG. 9;

FIG. 11 is a top plan view of a portion of the apparatus of FIG. 8 showing the flowline after installation on the wellhead guide structure; and

FIGS. 12 and 13 are detailed views of a portion of the apparatus of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 of the drawing, a wellhead guide structure 10 is shown communicating with a well 11 extending into the floor 12 of a body of water 13. Guide structure 10 includes a plurality of upwardly extending guide structure posts 14 (such as posts 14a, b, c & d of FIG. 2) having suitable bracing 15 extending therebetween. A flowline connector is carried by guide structure 10. Flowline connector 16 includes one or more outwardly flared flowline guide members (FIG. 2) in the preferable form of the bottom half of a horn 17 as shown in FIG. 3. Each of the bottom-half horns I7 is open at its flared end 18 for receiving a flowline therein, and, at the rear end, includes a split sleeve-type receptacle 19 (FIG. 3), open at the top, for receiving the pulling head of a flowline as will be discussed further hereinbelow. The flowline connector 16 is preferably fastened to the guide structure 10 before running the structure 10 into engagements with well I I as is well known in the art. The connector 16 also includes at least a pair of receptacles 16a for receiving lock down mechanism (not shown) therein as will be described further hereinbelow.

At this point, a conventional Xmas-tree-type assembly 20 is lowered into engagement with guide structure 10 as is also well known in the art. Thus, as seen in FIG. 4, Xmas tree assembly 20 includes guide arms 21 having a plurality of guide sleeves 22 thereon for slidably engaging posts 14 (only two such sleeves being shown in FIG. 4). Conventional pipe string connecting means 23 is carried at the upper end of assembly 20. At least one wellhead flowline 24 preferably extends in a loop from fluid engagement with the portion of assembly 20 in fluid communication with well II for removing fluids therefrom. Obviously, each horn 17 may include a flowline 24 extending thereto. A pipe coupling 25a is disposed at the free end of flowline 24 and is adapted to be coupled to the flowline which is to be connected to horn 17 for flowing fluids therethrough as will be discussed further hereinbelow.

These operations, i.e., the installation of the guide structure 10 and Xmas-tree assembly 20 as discussed hereinabove, may be carried out from a conventional platform structure, such as a large drilling rig (floating or bottom-supported). After the tree assembly 20 is installed, the drilling rig (not shown) moves off and a smaller work barge 25 is moved to install and connect the flowlines. Thus, vessel 25 is shown in FIG. 5 floating on water surface 26 and anchored over well I l. The

platform structure may be permanently anchored in place or, as shown, be temporarily anchored by mooring lines 27 or the like leading to suitable anchors (not shown) on the ocean floor l2. Vessel 25 preferably includes suitable working equipment thereon, such as a crame 28, a work platform 29, etc. A plurality of guidelines are connected to the guide structure posts 14 of guide structure 10. The guidelines are preferably connected at least to the posts 14 adjacent to the flowline connector 16. For example, the guidelines are connected to posts 14b, c & d of FIG. 2, only guidelines 30 and 31 (connected to posts 14d and 14 c respectively) being shown in FIG. 5. These guidelines may be connected to the posts by any suitable means known in the art, as for example, by either underwater divers or remote means (not shown).

Referring now to FIG. 6, a pulling tool fixture 32 is used in pulling the flowlines into flowline connector 16. The tool fixture 32 includes four individual upper halfs of horns 33 (FIG. 7) adapted to mate with the lowerhalf-horns 17 of connector 16 as will be discussed further hereinbelow with respect to FIG. 8. As can be seen in FIG. 6, pulling tool 32 includes a pressure-actuated locking mechanism 34 adapted to engage mating receptacle 16a (FIG. 2) on connector assembly 16.

Referring now to FIG. 12, locking mechanism 34 is shown about to be lowered into engagement with receptacle 16a, various portions of the apparatus of my invention being omitted for convenience of illustration. Receptacle 160 includes a generally U-shaped housing 90, open at its upper end, and an annular groove 91 extending about its inner wall 92. The upper portion of inner wall 92 may be upwardly and outwardly tapered, as at taper 93.

Locking mechanism 34 includes an outer body member 94 having an upper flange 95 and being slightly tapered inwardly and downwardly at its lower end as at taper 96. Locking means 97 is disposed in an aperture 98 in body member 94. The outer extent of locking means 97 is generally flush with the outer wall of body member 94 prior to installation in receptacle 16a.

Mechanism 34 includes a member 99 slidably disposed within body member 94. Member 99 has a reduced portion 100 at its lower end and an enlarged portion 101 at its upper end. Mid body portion 102 is thus greater than portion 100 but less than portion 101. Portion 101 may include a groove 103 therein for receiving a conventional O-ring 104. The inner wall 105 of body member 94 may include a similar groove 106 for receiving a like O-ring 107. A plate 108 closes the top of flange 95 and is sealed thereto by any suitable means. A latching inlet 109 extends through plate 108 for connection to a hydraulic hose 110 for latching mechanism 34 is receptacle 16a. An unlatching outlet 11] extends through plate 108 and body member 94 for connection to a hydraulic hose 112 for unlatching mechanism 34 from receptacle 16a.

Referring now to FIG. 13, mechanism 34 is lowered into engagement with receptacle 16a and hose 110 is actuated thus forcing member 99 down within body member 94. Locking means 97 is pushed by portion 102 outwardly and engages groove 91 on the inner wall 92 of receptacle 16a. By means of hose 112, fluid may be withdrawn from the coupled position of FIG. 13 and the mechanism 34 may be disengaged from receptacle 16a.

A pair of sheaves 35 and 36 are carried by pulling tool fixture 32 (see also FIGS. 6, 7 & 8 for each horn 33). Pulling tool fixture 32 also includes suitable guide sleeves thereon sleeves 37 and 38 being shown in FIGS. 6 and 8, for engaging posts 14d and 140, respectively (the guide sleeve for post 14b not being shown for convenience of illustration). The pulling tool fixture 32 is lowered on pipe 39 which preferably include a bumper sub (telescopic element) 39-0 to accommodate vertical heaving motions of the work barge 25. A hydraulic hose (or hoses)not shownmay be attached to pipe landing string 39b (FIG. 9) to actuate the lock-down mechanism 34 on the pulling tool fixture 32.

A pulling wire 40, extending from surface vessel 25 (see FIG. 8) extends under sheave 35, then over sheave 36 where it is adapted to be attached to a suitable flowline (see the dotted lines in FIG. 6--the free end of wire 40 not shown in FIG. 6 as attached to a flowline). Preferably, wire 40 is prethreaded onto sheaves 35 and 36 prior to lowering pulling tool fixture 32 into place.

Referring now to FIG. 8, the pulling tool fixture 32 is lowered on pipe running string 39b into engagement with flowline connector 16. As can be seen, the upperhalf born 33 mates with the lower-half horn 17 to form a complete horn 41. Guide sleeves 37 and 38 telescopingly fit over posts 14 as shown and discussed hereinabove. The locking mechanism 34 (FIG. 6) is actuated through hydraulic hoses attached to pipes 39 and 390 thus locking pulling tool fixture 32 to flowline connector 16. The free end 42 of pulling wire 40 now extends through the horn 41.

As can be seen in FIG. 9, the free end 42 of wire 40 is next attached to a flowline 43 which is being payed out from a suitable spool barge 44 or the like floating on the water surface 26 a suitable distance laterally of well 11, say 600 feet. Barge 44 preferably carried suitable pipe laying equipment, such as a stinger 45, a pipe reel 46, pipe tensioning means (not shown) and the like. Small diameter pipe is often installed by reeling the pipe off a large spool.

Each flowline that is to be connected to the horns 41 formed by flowline connector 16 and pulling tool fixture 32 is preferably equipped with a pulling head 47 (see FIG. 10) in selective fluid communication with the flowline adapted to engage the split sleeve, receptacle [9 of FIG. 3. Split sleeve receptacle 19 includes a plurality of apertures, such as apertures 49 and 50 extending therethrough for receiving retaining assemblies 51 and 52, respectively. Each retaining assembly comprises a pin 53 having an enlarged head 54 at its outer end (i.e., greater than the diameter of apertures 49 and 50) and an inner piston-type member 55 adapted to slide within a cavity 56 formed within a housing 57 screw-threaded or otherwise mounted on the outer wall 58 of receiving fixture 48, as at threads 59. Pin 53 passes through an aperture 60 in the upper wall 61 of housing 57. A spring 62 is disposed between pistontype member 55 and wall 61 for biasing the retaining assembly 51 (or 52) inwardly of the receiving fixture 48. Each pin 53 includes at its innermost end an enlarged wedge-type portion 63, fastened thereon as by threads 64, which is adapted to engage an abutment surface 65 on pulling head 47. In this manner, by acmating pins 53, the split sleeve receptacle 19 may be released from engagement with pulling head 47. Wedge-type portion 63 and surface 65 prevent rearward movement of pulling head 47 while a wedgeshaped portion 66 on the forward end 67 of receptacle 19 engages an abutment surface 68 to prevent the forward movement of head 47. Surface 68 is so configured as to fit into rear end 19 of born 41 as will be discussed hereinbelow. Thus, spring-loaded assemblies 51 and 52 capture pulling head 47 when the head 47 is in proper position in receptacle 19.

The free end 42 of pulling wire 40 is prepared with a conventional spelter socket-69 to fit into a hollow sleeve 70a in a removable pulling tool 70. A locking sleeve 71 surrounds sleeve 70a and includes an annular groove 72 for receiving a diver-operated tool (not shown) for unscrewing the pulling head tool 70 from pulling head 47. Sleeve 71 includes a reduced diameter portion 74 at its rear end. A skirt 75 is secured to the outer surface 76 of sleeve 71 to protect threads on the pipeline pulling head 47. The forward end 67 of pulling head 47 includes a forwardly directed extension portion in the form of a ring 78 or the like which fits into the annular space 77 and releasably locks therein, as by the engagement of 79 on ring 78 with threads 80 on reduced diameter portion 74 as can be seen in FIG. 10. When the pulling wire 40 is to be attached to flowline 43, as discussed hereinabove, the free end 42 of pulling wire 40 is equipped with the removable pulling tool 70 (see FIGS. 6 and 8), and the tool 70 is threaded onto pulling head 47 and head 47 is pulled from barge 44 into engagement with the receptacle 19 of connector 16 shown in FIG. 9.

As seen in FIG. 9, flowline 43 is pulled into engagement with horn 41 by hoisting in on the pulling wire 40 at work vessel 25 until the pulling head 47 engages horn 41 and is captured by latching dogs -63. The removable pulling tool 70 is removed from the pulling head 47 as by releasing ring 78 from engagement in annular space 77. This may be accomplished by sending a diver from vessel 25 to the wellhead structure 10. The pulling tool 70 may then be recovered and other flowlines may be connected to each horn 41 in like manner.

It is now necessary that interconnecting means be provided between coupling 25a on the wellhead flowline 24 (or flowlines) and the pulling head 47 of flowline 43. Thus, as seen in P16. 11, this may be accomplished by a diver installing a connecting spool 83 having mating couplings 85 and 86 at each end for engaging both coupling 25a and pulling head 47, respectively, the spool 83 having a telescoping interpiece 84 for varying the length thereof. Alternatively, spool 83 may have a fixed length with a long nut or the like (not shown) at one end for pulling up" and thus engaging coupling 25a of the loop of wellhead flowline 24.

Obviously, each flowline 43 may be pulled either singularly or simultaneously into engagement with each horn 41 in like manner. Thus, although it is possible to prethread the pulling wires 40 to pull all the flowlines 43 in one operation, it is preferred to raise the pulling tool 70 after each connection to rethread the pulling wires 40 therein.

I claim as my invention:

l. A method for connecting a flowline to a wellhead extending into the floor of a body of water, said flowline having a pulling head attached thereto, said wellhead having the lower half of a pulling head receiving fixture attached thereto, said method comprising the steps of:

lowering and suitably mating the upper half of said pulling head receiving fixture with the lower half of said pulling head receiving fixture;

attaching a removable pulling tool having a wireline secured thereto to the pulling head of said flowline;

pulling said wireline and thus said tool through said fixture until said attached pulling head engages said fixture; and

removing said pulling tool from said pulling head fixture.

2. The method of claim 1 including the step of providing fluid communication between said pulling head within said fixture and said wellhead.

3. The method of claim 1 wherein the step of pulling said wireline and thus said tool through said fixture includes the step of pulling said tool through said fixture until said tool locks in said fixture.

4. The method of claim 1 wherein the step of pulling said wireline through said fixture includes the step of passing said wireline from a work vessel floating on the water surface through said fixture in slidable relation thereto, and securing said tool thereto prior to attaching said tool to said pulling head.

5. The method of claim 1 wherein the step of pulling said wireline includes the step of paying out said attached flowline from a pipe laying vessel on the water surface while pulling said wireline through said fixture.

6. Apparatus for connecting flowlines to a wellhead structure extending into the floor of a body of water, comprising:

at least one flowline having a pulling head attached thereto and in selective fluid communication therewith; pulling head receiving fixture means adapted to receive said pulling head said fixture means comprising at least one lower half horn-shaped member fixed to said wellhead structure, said pulling head fixture having at least one mating upper half-horn-shaped member selectively removable on said wellhead structure, said upper and lower half-horn-shaped members forming at least one unitary complete horn-shaped member having a flared mouth and a rear end communicating therewith for receiving said pulling head therein; and

said pulling head including selectively releasable pulling tool means thereon adapted to engage said pulling head for pulling said pulling head through and into engagement with said pulling head fixture means.

7. The apparatus of claim 6 wherein said pulling tool means includes a wireline extending through said fixture means in slidable relationship thereto.

8. The apparatus of claim 6 including interconnecting means extending between said wellhead structure and said pulling head for providing fluid communication therebetween. 

1. A method for connecting a flowline to a wellhead extending into the floor of a body of water, said flowline having a pulling head attached thereto, said wellhead having the lower half of a pulling head receiving fixture attached thereto, said method comprising the steps of: lowering and suitably mating the upper half of said pulling head receiving fixture with the lower half of said pulling head receiving fixture; attaching a removable pulling tool having a wireline secured thereto to the pulling head of said flowline; pulling said wireline and thus said tool through said fixture until said attached pulling head engages said fixture; and removing said pulling tool from said pulling head fixture.
 2. The method of claim 1 including the step of providing fluid communication between said pulling head within said fixture and said wellhead.
 3. The method of claim 1 wherein the step of pulling said wireline and thus said tool through said fixture includes the step of pulling said tool through said fixture until said tool locks in said fixture.
 4. The method of claim 1 wherein the step of pulling said wireline through said fixture includes the step of passing said wireline from a work vessel floating on the water surface through said fixture in slidable relation thereto, and securing said tool thereto prior to attaching said tool to said pulling head.
 5. The method of claim 1 wherein the step of pulling said wireline includes the step of paying out said attached flowline from a pipe laying vessel on the water surface while pulling said wireline through said fixture.
 6. Apparatus for connecting flowlines to a wellhead structure extending into the floor of a body of water, comprising: at least one flowline having a pulling head attached thereto and in selective fluid communication therewith; pulling head receiving fixture means adapted to receive said pulling head said fixture means comprising at least one lower half horn-shaped member fixed to said wellhead structure, said pulling head fixture having at least one mating upper half-horn-shaped member selectively removable on said wellhead structure, said upper and lower half-horn-shaped members forming at least one unitary complete horn-shaped member having a flared mouth and a rear end communicating therewith for receiving said pulling head therein; and said pulling head including selectively releasable pulling tool means thereon adapted to engage said pulling head for pulling said pulling head through and into engagement with said pulling head fixture means.
 7. The apparatus of claim 6 wherein said Pulling tool means includes a wireline extending through said fixture means in slidable relationship thereto.
 8. The apparatus of claim 6 including interconnecting means extending between said wellhead structure and said pulling head for providing fluid communication therebetween. 